I'm having troubles locating decent 40mm*40mm 12V TECs. I have only found 80w plates in 12v AND 40mm. I was hoping to find something in the 150w+ range. The ones that I have found in the required size and wattage, have been 24V.

And if that's not possible, does anyone know of a gpu pelt block that will take a 50mm*50mm TEC?

Yeah, I have it. Many of the TECs I've been seeing tho are 24V. I really think DD just screwed up, and the 178W TEC on their site is 12V. I think that because Swiftech's TEC block is 12v with the same wattage. Might just try getting the Swifty block. MCW60 is a solid performer.